US2958172A

US2958172A - Apparatus for packaging articles in a printed plastic sheet

Info

Publication number: US2958172A
Application number: US643354A
Authority: US
Inventors: Branche Harvey W La
Original assignee: WASHINGTON STEEL PRODUCTS Inc
Current assignee: WASHINGTON STEEL PRODUCTS Inc
Priority date: 1957-03-01
Filing date: 1957-03-01
Publication date: 1960-11-01
Anticipated expiration: 1977-11-01

Description

Nov. 1, 1960 H. w.- LA BRANCHE APPARATUS FOR PACKAGING ARTICLES IN A PRINTED PLASTIC SHEET Filed March 1, 1957 2 Sheets-Sheet 1 z e 4 2 3% mn 5 N E r 4 MB 3 [G L w W H r A H m f e w 5 II n m w H 2 2 m m \CDWWLM i 7 8L 3 0 j... 4 M

Nov. 1, 1960 H. w. LA BRANCHE APPARATUS FOR PACKAGING ARTICLES IN A PRINTED PLASTIC SHEET 2 Sheets-Sheet 2 Filed March 1, 1957 INVENTOR. Harvey WILa Bran chc M [292% Hf? g.

APPARATUS FOR PAQKAGENG ARTICLES IN A PRINTED PLA'STHI SHEET Harvey W. La Branche, Tacoma, Wash, assignor to Washington Steel Products, Inc, Tacoma, Wash, a corporation of Washington Filed Mar. 1, 1957, Ser. No. 643,354

1 Claim. (Cl. 53-141) This invention relates to a method for packaging articles in a printed plastic sheet.

In the packaging art it frequently is desirable to package articles in sheets of clear plastic in order to protect the articles while still permitting inspection of them and display of their inherent beauty. This may be accomplished by heat softening a selected transparent thermoplastic material, wrapping it about the article while it is softened and then cooling it to harden it.

In this procedure it is desirable to apply to the package a printed message indicating, for example, the character of the goods, their source and price, and related information. However, application of such a printed message is difiicult of accomplishment because of the distortion occurring in the plastic during the packaging operation.

Various procedures heretofore have been employed or suggested for achieving the desired result. In accordance with one method, the articles are packaged in clear plastic against a cardboard backing sheet upon which the message is imprinted. This procedure is subject to the disadvantage of increased cost attendant upon the use of the backing sheet, which costs nearly as much as the plastic itself and which requires special machinery and handling for its use. Also, the life of the backing sheet and the properties of the adhesive used for uniting the backing sheet and the plastic sheet are variable. Still further, the final product is subject to warping because of the unbalanced construction.

In another proposed procedure the plastic packaging sheet is preprinted with the message, allowance being made for the distortion occurring during packaging with the object in view of pulling the message into line during packaging. This is difficult of accomplishment, however, because of variable plastic properties, heater voltage, and atmospheric conditions. These and other factors make this procedure impractical and indeed preclude its application altogether where intricate work is involved.

Still further, it has been proposed to print the package after the packaging operation has been completed. However, this requires a special press. Also, each of the diverse items packaged would require its own special and costly printing platen designed to provide clearance for the packaged article when the sheet is printed.

Accordingly it is the general object of this invention to provide a method and apparatus for packaging articles in a printed plastic sheet without distortion of the printing to form a final package which is stable, inexpensive, and durable and which permits viewing of the packaged article while reading the printed message directly associated therewith.

The manner in which the foregoing and other objects of this invention are accomplished will be apparent from the accompanying specification and claim considered together with the drawings, wherein:

Fig. l is a view in side elevation of apparatus which may be employed for packaging articles in a printed plastic sheet in accordance with the herein described method, partly broken away to show the interior con 2,958,172 Patented Nov. 1, 1960 struction, the sheet being positioned for clamping and heating.

Fig. 2 is a sectional view taken along line 22 of Fig. 4 and illustrating the heat-softened, clamped sheet draped across the articles;

Fig. 3 is a sectional view taken along line '33 of Fig. 4 and illustrating the sheet wrapped around the articles;

Fig. 4 is a plan view of the apparatus illustrated in Figs. 1-3; and

Fig. 5 is a perspective view of a package produced by the method of the present invention.

Generally stated, the herein described method of packaging articles comprises providing a thermoplastic sheet having a printed portion, which it is desired to preserve undistorted, and a packaging portion which is to be Wrapped around the article. The sheet is placed across an article to be packaged with the packaging portion opposite the article. Heat is applied selectively to the packaging portion for softening the same, after which the article and the sheet are moved relatively to each other, wrapping the softened portion about the article. Thereafter the sheet is cooled for hardening it and forming the final package.

contemporaneously with the foregoing sequence, the margins of the sheet may be softened selectively and pressed against a molding surface for forming a marginal bead about the package. This lends stiffness and rigidity to the package so that it may be handled more readily.

Considering the foregoing in greater detail and with particular reference to the drawings:

The presently described packaging method may be applied to the packaging of a diversity of miscellaneous items where it is desired to protect the item, but at the same time permit inspection of it. Illustrative of such items are fishing lures, cutlery, small tools, door and drawer knobs, hinges, clusters of screws and bolts, and the like. For purposes of illustration, it is described herein in connection with the packaging of a plurality of screws 10.

To package the articles, they are placed in apparatus including a forming plate or platen 12 mounted on a table 14 having a smooth upper surface area surrounding the formingplate.

The upper surface of plate 12 is subdivided by a plurality of ridges 16 which define the plate areas to be employed for the production of each individual package. The interior of the plate is penetrated by a number of communicating passageways all of which are connected to a source of vacuum. As is evident from Fig. 3, these passageways include passageways 18 located on both sides of ridges 16; passageways 20 located adjacent the articles to be packaged; and

central passageways

22, 24 communicating with each other and with a duct 26 leading to a source of vacuum, not illustrated.

Platen 12 is enclosed by a reciprocatable clamping frame assembly which also serves to define a vacuum forming box. In the illustrated form, the lower clamping frame 28 comprises a rectangular member dimensioned to enclose platen 12. Its undersurface is provided with a sealing ring 30 which may be brought into sealing relationship with the smooth upper surface of table 14. Piston rods 32 of fluid actuated cylinders not illustrated are connected to frame member 28 for reciprocating the frame assembly in a vertical direction.

A second sealing ring 34 is embedded in the upper surface of frame member 28. This ring functions to form a seal with a sheet of thermoplastic material 36- which may be placed across the open top of lower frame member 28 and which is used for packaging the articles 10 lying on platen 12. Accordingly, the packaging areas of the sheet which lie opposite the articles may or may not be left clear. However, the areas which do not thus overlie the articles may be preprinted with an inscription such as is illustrated in Figs. 4 and 5.

The clamping frame assembly also includes upper clamping unit 38 hinged by means of hinges 40 to the companion clamping unit 28 with which it registers; An operating handle 42 is provided on frame unit 38 for opening and closing the frame assembly as required to insert and withdraw plastic sheet 36 Means also are provided for applying heat selectively to the packaging areas of the plastic'sheet: Such means include a heating unit in combination with a shielding unit. The heating unit, indicated generally at 44 in Fig. 2, includes a substantially rectangularframe 46 dimensioned to register with

clamping frames

28, 38. An operating handle 48 is connected to the frame and an electric heating element 50 is supported thereby. The entire heating unit is mounted on a track or otherwise for movement toward and away from plastic sheet 36 clamped in the clamping frame.

The shielding unit of the selective heating assembly comprises a plate 52 fastened by means of screws 54, or otherwise, to the top of upper clamping frame 38. As is apparent from Figs. 2 and 3, shield 52 is formed with openings in predetermined locations. Thus open ings 56, which may assume the form of linearly disposed, round or elongated openings, register with ridges 16 on platen 12. Openings 58, which are of comparatively large size, overlie the unprinted areas of plastic sheet 36 and articles 10 on platen 12. Since shield 52 is spaced from plastic sheet 36 by a distance equal to the thickness of upper clamping frame 38, heat directed against the shield by heating unit 44 will be somewhat diffused, but will be directed against and soften those portions of the plastic sheet which are opposite articles 10 and ridges 16.

- Operation The manner of operation of the above described apparatus is as follows:

Articles 10 to be packaged are placed on platen 12 opposite vacuum passageways 20 where they are held by gravity, magnetic attraction or otherwise. The clamping frame assembly is placed in the raised, open position of Fig. 1.. A sheet 36 of suitable thermoplastic material is, placed across the opening of lower clamping frame member 28 after which upper clamping frame member 38 is lowered into clamping engagement with the lower frame member.

Heat unit'50 then is energized or, if continuously energized, moved adjacent the apparatus. Heatthereupon is radiated against shield plate 52 which permits application of heat to the plastic sheet only in those areas directly below

openings

56, 58. The application of heat is continued until these areas of the plastic have been softened.

Next, piston rods 32 are retracted, which draws the clamping frame and the plastic sheet down over the platen and across the articles 10. A vacuum mold box defined by the upper surface of table 14, platen 12, the side walls of clamping frame 28 and the plastic sheet itself accordingly is formed.

Vacuum is applied to the interior of the mold box via duct 26 communicating

with'passageways

18, 20, 22 and 24. The softened areas of the plastic thus are sucked down; those opposite ridge 16 being formed in a continuous bead about the articles 10, and those opposite the articles themselves being drawn about and tucked under the articles, encasing and packaging them.

After the heat source has been removed, the plastic sheet is permitted to cool and harden. The clamping frame then may be opened and the sheet with encased articles stripped from the platen 12. Where, as illustrated, several package units are formed in one operation, these may be cut apart from each other.

The final package is illustrated in Fig. 5." It comprises a plastic sheet 60 having a marginal bead 62 conforming to the dimensions of ridge 16 on platen 12. This stiifens the sheet and lends rigidity to it for better handling during merchandising operations. The articles 10 are encased inthe clear area of the plastic. The preprinted message appears above the articles, undistorted and legible.

It is to be understood that the form of my invention herewith shown and described is to be taken as a preferred example of the same and that various changes in the shape, size and arrangement of parts may be made without departing from the spirit of my invention or the scope of the subjoined claim.

Having thus described my invention, I claim:

Apparatus for packaging an article in a thermoplastic sheet having printed and packaging areas, comprising support means for supporting an article to be packaged, peripheral bead-forming means on the. support means, means for supporting a thermoplastic sheet across the bead-forming means with the packaging area thereof.

overlying the article, heating means adjacent the sheet supporting means on the side thereof opposite the article supporting means and operable to heat and soften a thermoplastic sheet, heat shielding means interposed between the heating means and the sheet supporting means and having openings therein disposed for registry with the bead-forming and packaging areas of a thermoplastic sheet, whereby to heat and soften the latter and to shield the printed area from such heat, means for lowering the sheet supporting means to lower the selectively heated areas of the sheet onto the bead-forming means and the article, and means for forcing the softened areas of the sheet about the bead-forming means and article and the printed unheated area of the sheet onto the article supporting means, whereby to maintain said printed area undistorted, the heated areas of the sheet thereafter being cooled to harden the same, whereby to produce a peripherally reinforced package sheet confining an article in the packaging area thereof and displaying an undistorted printing on the printed area.

References Cited in the file of this patent UNITED STATES PATENTS 1,980,022 Whitehouse Nov. 6, 1934 2,511,024 Toulmin June 13, 1950 2,536,048 Flanagan Ian. 2, 1951 2,690,593 Abercrombie Oct. 5, 1954 2,749,572 Nowak June 12, 1956 2,750,719 Wandelt June 19, 1956 2,836,941 Hultkrans et a1. June 3, 1958 2,855,735 Groth Oct. 14, 1958 FOREIGN PATENTS 201,271 Australia Mar. 19, 1956